Under British Olympic Association rules, Chambers would also be barred from Olympic participation for life if found guilty of doping.

Chambers' statement said that his trainer, Remi Korchemny, had instructed him to use as his nutritionist Victor Conte of Balco Laboratories - the company at the centre of the THG scandal.

It added that when Chambers heard of his positive test, he had challenged Conte, who had assured him "that all supplements given were within IAAF rules".

Chambers' lawyer added: "I understand that Mr Conte continues to deny that the supplements he prepared for my client and other athletes contain any illegal substances. This is a serious matter that the US authorities are investigating."

Lyn Davies, the president of UK Athletics and a former Olympic long jump champion, declined to comment directly about the Chambers case.